What are some reasons that the salinity of seawater could be increasing in some regions?

What are some reasons that the salinity of seawater could be decreasing in some regions?

What would happen to seawater density if global warming causes sea surface temperatures to rise? What if global warming increases evaporation? What is the net result?

Some scientists fear that warmer temperatures in the Arctic will cause more ice to melt into the region of the North Atlantic where deep water forms. If this happens what will be the effect on global thermohaline circulation?

In the case described above, what could be the effect on the Gulf Stream? How might that alter the climate of the British Isles and Western Europe?